In recent years, a new type of radiation detector has been developed in which a capillary plate made of lead glass and functioning as a microchannel plate (MCP) is operated as an imaging type capillary gas proportional counter (CGPC) (see Non-Patent Documents 1 to 8). Recently, a gas electron multiplier (GEM) has received attention as another radiation detector capable of detecting a two-dimensional position of an X-ray or the like (see Non-Patent Documents 10 to 12).
Furthermore, the present inventor has further improved a conventional CGPC, and has suggested a capillary plate capable of sufficiently reducing a noise level and a new CGPC using the plate (Patent Document 1), and a CGCP which is excellent in shock resistance and handling property as compared with the GEM and in which uniformity of a sensitivity distribution is further improved (Patent Document 2).    Non-Patent Document 1: H. Sakurai et al., “A new type of proportional counter using a capillary plate”, Nucl. Instr. and Meth. In Phys. Res. A374 (1996) 341 to 344.    Non-Patent Document 2: H. Sakurai et al., “Characteristics of capillary gas proportional counter”, SPIE Proceedings Reprint, vol. 2806 (1996) 569 to 576.    Non-Patent Document 3: H. Sakurai et al., “Detection of photoabsorption point with capillary imaging gas proportional counter”, IEEE Trans. on Nucl. Sci. vol. 49, No. 3, (2002).    Non-Patent Document 4: M. Tsukahara et al., “The development of a new type of imaging X-ray detector with a capillary plate”, IEEE Trans. on Nucl. Sci. vol. 49, No. 3, (1997) 679 to 682.    Non-Patent Document 5: H. Sakurai et al., “The form of X-ray photoelectron tracks in a capillary gas proportional counter”, IEEE Trans. on Nucl. Sci. vol. 46, No. 3, (1999) 333 to 337.    Non-Patent Document 6: H. Sakurai, “Imaging gas proportional counter with capillary plate”, Radiation vol. 25, No. 1, (1999) 27 to 37.    Non-Patent Document 7: H. Sakurai et al., “New type of imaging X-ray detector using a capillary plate”, SPIE Proceedings Reprint, vol. 3114 (1997) 481 to 487.    Non-Patent Document 8: T. Masuda et al., “Optical imaging capillary gas proportional counter with penning mixtures”, IEEE Trans. on Nucl. Sci. vol. 49, No. 2, (2002) 553 to 558.    Non-Patent Document 9: Nishi, Yu.; Tanimori, Y.; Ochi, A.; Nishi, Ya.; Toyokawa, H., “Development of a hybrid MSGC with a conductive capillary plate.”, SPIE, vol. 3774 (1999) 87-96.    Non-Patent Document 10: F. Sauli, Nucl. Instr. and Meth. A 368 (1977) 531.    Non-Patent Document 11: F. A. F. Fraga, et al., Nucl. Instr. and Meth. A 442 (2000) 417.    Non-Patent Document 12: D. Mormann, et al., Nucl. Instr. and Meth. A 504 (2003) 93.    Patent Document 1: Japanese Patent Application Laid-Open No. 2004-241298    Patent Document 2: Japanese Patent Application Laid-Open No. 2005-32634